I was having a look at one of my Magento 2 databases and it looked quite large to me. It was 2.5Gb, which in the scheme of things is probably not massive, but it was much larger than I thought it should be for the size of site I was dealing with.
So I decided to find out what was filling it up!
It came down to a database table called reporting_system_updates which I believe is related to New Relic reporting which I had enabled.
Here is a 3 minute video of what I found when I truncated it!